<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>摇一摇撒金币</title>
    <meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no,minimal-ui" />
    <style>
        body{margin:0;padding:0;}
        input{position:absolute;z-index:1000}
        canvas{position:absolute;top:0;left:0;}
    </style>
    <script>
        function Coin(opts){
            //默认参数
            this.defaults={
                coinSrc:"http://gw.alicdn.com/tps/i3/TB1QJ5DGpXXXXaBXXXXuv2kGFXX-39-39.png_40x40Q50s150.jpg",     //金币图片地址
                audioSrc:"http://download.taobaocdn.com/freedom/26370/media/shake.mp3",	//金币音频地址
                coinWidth:20,           //金币宽度
                coinHeight:20,          //金币高度
                density:30
            };
            this.settings=this._extendDeep(this.defaults,opts);   //深拷贝
            this.density=this.settings.density;                   //密度，即金币个数
            this.timeLag=1000;                                    //金币散落的事件间隔，数字越大表示间隔越大
            this.coinWidth=this.settings.coinWidth;               //金币宽度
            this.coinHeight=this.settings.coinHeight;             //金币高度
            this.wrapWidth=0;
            this.wrapHeight=0;
            this._init();
        }
        Coin.prototype={
            constructor:Coin,
            /**
             * 动画初始化方法
             * @method _init
             **/
            _init:function(){
                //初始化包括尺寸大小
                this.wrapWidth=document.documentElement.clientWidth;
                this.wrapHeight=document.documentElement.clientHeight;
                this._requestAnimationFrame();
                this._createCanvas();
                this._createAudio();
            },
            /**
             * 对象深拷贝方法
             * @method _extendDeep
             * @param  {object} parent 父对象
             {object} child  子对象
             @return {object} child  父对象继承给子对象
             **/
            _extendDeep:function(child,parent){
                var i,
                    toStr = Object.prototype.toString,
                    astr = "[object Array]";
                child = child || {};
                for (i in parent) {
                    if (parent.hasOwnProperty(i)) {
                        if (typeof parent[i] === "object") {
                            child[i] = (toStr.call(parent[i]) === astr) ? [] : {};
                            extendDeep(parent[i], child[i]);
                        } else {
                            child[i] = parent[i];
                        }
                    }
                }
                return child;
            },
            /**
             * requestAnimationFrame做兼容
             * @method _requestAnimationFrame
             **/
            _requestAnimationFrame:function(){
                var lastTime = 0;
                var vendors = ['webkit', 'moz'];
                for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
                    window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
                    window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] ||    // name has changed in Webkit
                        window[vendors[x] + 'CancelRequestAnimationFrame'];
                }
                if (!window.requestAnimationFrame) {
                    window.requestAnimationFrame = function(callback, element) {
                        var currTime = new Date().getTime();
                        var timeToCall = Math.max(0, 16.7 - (currTime - lastTime));
                        var id = window.setTimeout(function() {
                            callback(currTime + timeToCall);
                        }, timeToCall);
                        lastTime = currTime + timeToCall;
                        return id;
                    };
                }
                if (!window.cancelAnimationFrame) {
                    window.cancelAnimationFrame = function(id) {
                        clearTimeout(id);
                    };
                }
            },
            /**
             * 创建canvas画布
             * @method _createCanvas
             **/
            _createCanvas:function(){
                var _self=this;
                this.canvas=document.createElement('canvas');
                this.canvas.setAttribute("data-id",Date.now());
                if(!this.canvas.getContext){
                    alert("您的浏览器不支持canvas");
                    return;
                }
                this.context=this.canvas.getContext('2d');
                this.canvas.width=this.wrapWidth;
                this.canvas.height=this.wrapHeight;
                var oBody=document.getElementsByTagName('body')[0];
                oBody.appendChild(this.canvas);
                this._createCacheCanvas();
            },
            _createCacheCanvas:function(){
                var _self=this;
                this.cacheCanvas=document.createElement('canvas');
                this.cacheContext=this.cacheCanvas.getContext('2d');
                this.cacheCanvas.width=this.wrapWidth;
                this.cacheCanvas.height=this.wrapHeight;
                this.coinImg=new Image();
                this.coinImg.src=this.settings.coinSrc;
                this.coinImg.onload=function(){
                    _self._startCacheCanvasAnim();
                }
            },
            /**
             * 执行金币绘制动画
             * @method _startCanvasAnim
             **/
            _startCacheCanvasAnim:function(){
                var _self=this;
                var availWidth=this.cacheCanvas.width-this.coinWidth;
                var availHeight=this.cacheCanvas.height-this.coinHeight;
                //var disX=availWidth/this.density;  //每个硬币X轴的间距
                var coinRange=availWidth*this.density/(this.density+15);
                var rangeStart=(availWidth-coinRange)/2;
                var g=9.8*280;   //重力加速度
                var bPlayAudio=false;
                var coinAttrArr=[];  //存储金币下落过程中的一些属性参数
                for(var i=0;i<_self.density;i++){
                    coinAttrArr[i]={
                        rndX:Math.random(),                                    //存储金币开始降落x轴随机值
                        rndOrder:Math.round(Math.random()*_self.timeLag/17),   //存储金币撒落顺序的一个数组
                        time:0,									               //存储金币绘制的具体时间
                        top:0,                                                 //存储金币绘制距离顶部的距离
                        left:0,                                                //存储金币弹起后距离左边的距离
                        endSpeed:0,                                            //存储金币第一次接触地面的速度
                        bEnd:false,								               //存储金币是否触碰到地面
                        reDownSpeed:0,                                         //存储金币弹起后重新降落的速度
                        reDownHDelta:Math.random()*100+250,                    //存储金币弹起的高度参数，随机值250~350之间
                        rndOffsetX:Math.random()*0.06+0.97                     //存储金币x轴的偏移量，随机值0.97~1.03之间
                    }
                }
                var startTime =  Date.now();  //开始绘制前的时间
                function draw(){
                    var drawStart = Date.now();  //记录重绘的结束事件
                    var diff = (drawStart - startTime)/1000;  //计算每次重绘所需要的事件，单位为秒
                    startTime = drawStart;   //结束事件传给开始事件
                    _self.context.clearRect(0,0,_self.canvas.width,_self.canvas.height);  //清除画布，方便重绘
                    _self.cacheContext.clearRect(0,0,_self.cacheCanvas.width,_self.cacheCanvas.height);  //清除画布，方便重绘
                    _self.cacheContext.save();
                    //根据金币个数循环绘制金币
                    for(var i=0;i<_self.density;i++){
                        if((coinAttrArr[i].rndOrder==0&&coinAttrArr[i].time==0)){   //如果顺序为0，表示开始下落，同时下落的初始时间为0时，赋值初始时间
                            coinAttrArr[i].time=diff;
                        }
                        if(coinAttrArr[i].time>0){     //如果初始事件大于0，表示已经在下落过程中,则每次的初始时间递增
                            coinAttrArr[i].time=coinAttrArr[i].time+diff;
                        }
                        if(coinAttrArr[i].rndOrder==0){  //如果顺序为0，开始下落，则开始绘制金币
                            if(!coinAttrArr[i].bEnd){   //金币下落（过程一），自由落体运动
                                coinAttrArr[i].top=g*Math.pow(coinAttrArr[i].time,2)/2-_self.coinHeight;   //自由落体加速度运动，求下落的高度
                                //coinAttrArr[i].left=disX*coinAttrArr[i].rndX+i*disX;
                                coinAttrArr[i].left=coinRange*coinAttrArr[i].rndX+rangeStart;
                            }else if(coinAttrArr[i].endSpeed==0){   //金币弹起后在空中重新下落（过程三）
                                coinAttrArr[i].reDownSpeed=coinAttrArr[i].reDownSpeed*1.1;
                                coinAttrArr[i].top=coinAttrArr[i].top+coinAttrArr[i].reDownSpeed;
                                coinAttrArr[i].left=coinAttrArr[i].left*coinAttrArr[i].rndOffsetX;
                            }else{   //金币弹起（过程二）
                                coinAttrArr[i].endSpeed=-Math.abs(coinAttrArr[i].endSpeed*0.96);
                                if(Math.abs(coinAttrArr[i].endSpeed)<1) coinAttrArr[i].endSpeed=0;
                                coinAttrArr[i].top=coinAttrArr[i].top+coinAttrArr[i].endSpeed;
                                coinAttrArr[i].left=coinAttrArr[i].left*coinAttrArr[i].rndOffsetX;
                            }
                            //金币第一次降落超过地面时，将其高度设置和地面齐平
                            if(coinAttrArr[i].top>_self.cacheCanvas.height-_self.coinHeight&&!coinAttrArr[i].bEnd){
                                coinAttrArr[i].top=_self.cacheCanvas.height-_self.coinHeight;
                            }
                            //金币落地时，计算落地的速度
                            if(coinAttrArr[i].top==_self.cacheCanvas.height-_self.coinHeight){
                                coinAttrArr[i].endSpeed=g*coinAttrArr[i].time/coinAttrArr[i].reDownHDelta;
                                coinAttrArr[i].reDownSpeed=coinAttrArr[i].endSpeed/10;
                                coinAttrArr[i].bEnd=true;
                            }
                            //绘制金币
                            _self.cacheContext.drawImage(_self.coinImg,coinAttrArr[i].left,coinAttrArr[i].top,_self.coinWidth,_self.coinHeight);
                        }
                        coinAttrArr[i].rndOrder=coinAttrArr[i].rndOrder==0?0:coinAttrArr[i].rndOrder-1;//顺序每一次重绘则递减一次，直到为0时，代表开始下落
                    }
                    _self.cacheContext.restore();
                    _self.context.drawImage(_self.cacheCanvas,0,0,_self.canvas.width,_self.canvas.height);
                    var firstH=_self._maxNum(coinAttrArr,"top");//求降落过程中高度最大的金币高度
                    if(firstH>=_self.cacheCanvas.height-_self.coinHeight&&!bPlayAudio){
                        _self._playAudio();
                        bPlayAudio=true;
                    }
                    var lastH=_self._minNum(coinAttrArr,"top");//求降落过程中高度最小的金币高度
                    if(lastH<=_self.cacheCanvas.height+_self.coinHeight){ //最后一个金币高度超出canvas的高度停止重绘
                        window.requestAnimationFrame(draw);  //重绘，递回调用绘制方法
                    }else{
                        console.log("金币都撒完了");
                        _self._destory();
                    }
                }
                window.requestAnimationFrame(draw);  //第一次绘制
            },
            /**
             * 求最小值
             * @method _minNum
             * @param   {arr}    arr  属性数组
             {string} attr 数组下的属性名称
             * @return  {number}      返回数组下属性值最小的值
             **/
            _minNum:function(arr,attr){
                var tempArr=[];
                for(var i=0;i<arr.length;i++){
                    tempArr.push(arr[i][attr]);
                }
                return tempArr.sort(function(a,b){return a-b})[0];
            },
            /**
             * 求最大值
             * @method _minNum
             * @param   {arr}    arr  属性数组
             {string} attr 数组下的属性名称
             * @return  {number}      返回数组下属性值最大的值
             **/
            _maxNum:function(arr,attr){
                var tempArr=[];
                for(var i=0;i<arr.length;i++){
                    tempArr.push(arr[i][attr]);
                }
                return tempArr.sort(function(a,b){return b-a})[0];
            },
            /**
             * 创建音频对象
             * @method _createAudio
             **/
            _createAudio:function(){
                this.audio=document.createElement('audio');
                this.audio.setAttribute("preload","load");
                var oSource=document.createElement('source');
                oSource.setAttribute("src",this.settings.audioSrc);
                oSource.setAttribute("type","audio/mp3");
                this.audio.appendChild(oSource);
                var oBody=document.getElementsByTagName('body')[0];
                oBody.appendChild(this.audio);
            },
            /**
             * 播放音频
             * @method _playAudio
             **/
            _playAudio:function(){
                this.audio.play();
            },
            /**
             * 销毁canvas和audio
             * @method _destory
             **/
            _destory:function(){
                var oBody=document.getElementsByTagName('body')[0];
                oBody.removeChild(this.canvas);
                oBody.removeChild(this.audio);
            }
        }
    </script>
    <script>
        window.onload=function(){
            var oBtn=document.getElementById('btn1');
            init();
            oBtn.onclick=function(){
                var coin=new Coin();
            }
            var SHAKE_THRESHOLD = 400;
            var last_update = 0;
            var index=0;
            var x = y = z = last_x = last_y = last_z = 0;
            var w_curTime=0;
            function init() {
                if (window.DeviceMotionEvent) {
                    window.addEventListener('devicemotion', deviceMotionHandler, false);
                } else {
                    alert('not support mobile event');
                }
            }
            function deviceMotionHandler(eventData) {
                var acceleration = eventData.accelerationIncludingGravity;
                var curTime = new Date().getTime();
                if ((curTime - last_update) > 100) {
                    var diffTime = curTime - last_update;
                    last_update = curTime;
                    x = acceleration.x;
                    y = acceleration.y;
                    z = acceleration.z;
                    var speed = Math.abs(x + y + z - last_x - last_y - last_z) / diffTime * 10000;
                    var delta=Math.abs(x + y + z - last_x - last_y - last_z);
                    if (speed > SHAKE_THRESHOLD) {
                        if((curTime-w_curTime)>2000){
                            w_curTime!=0 && new Coin({density:Math.round(delta)});
                            w_curTime=curTime;
                        }
                    }
                    last_x = x;
                    last_y = y;
                    last_z = z;
                }
            }
        }
    </script>
</head>
<body>
<input type="button" value="撒金币" id="btn1" />
</body>
</html>